Platelet collection system

ABSTRACT

A single use system and kit for producing blood platelet concentrates is described herein. In a preferred form, the kit includes a bag set in which compartments containing blood components are adjacent to to separate compartments which can be inflated to express the blood components after their separation by centrifuging.

This is a continuation of U.S. Ser. No. 10/014,375, filed Oct. 26, 2001,now U.S. Pat. No. 6,413,000, which is a division of U.S. Ser. No.09/525,573, filed Mar. 15, 2000, now U.S. Pat. No. 6,325,750, whichclaimed benefit of provisional application 60/124,385, filed Mar. 15,1999.

TECHNICAL FIELD OF THE INVENTION

This invention relates to processing whole blood into platelet-richplasma and, more particularly, to improvements in blood processingsystems for generating platelet-rich plasma from autologous blood.

BACKGROUND OF THE INVENTION

The science and effectiveness of using platelet-rich plasma derived fromthe patient's own blood in surgery are documented in medical, trade andscience journals. A known method for the preparation of platelets fromwhole blood is described in the American Association of Blood Bank'sTechnical Manual, 12th Edition, 1996, at pages 700-701, Method 9.11. Asystem employing this method collects the patient's whole blood into acollection unit with two integrally-attached transfer containers. Theblood is collected into the collecting container, the other two transfercontainers are collapsed, and the two transfer containers with thecollecting container are subjected to a “soft spin” in a centrifuge,which brings the plasma to the top of the collecting unit, leaving redcells at the bottom. In the next step, the collecting containercontaining the blood is squeezed in a plasma extractor to force theplatelet-rich plasma into one of the transfer containers through aconnecting tube. A fraction comprising red cells remains behind in thecollecting container, which is then removed. Next, the two transfercontainers, the first being empty and the second containing the plasma,are subjected to a “heavy spin” in a centrifuge to concentrate plateletsat the “bottom” of the second transfer container, leaving aplatelet-poor fraction of the plasma (PPP) above the plateletconcentrate (PC) in the second transfer container. The following stepsqueezes the second transfer container to express the PPP into the firsttransfer container. The platelet concentrate (PC) is then resuspendedand collected for use. This system uses a process requiring six separatesteps, including two centrifugal steps and two separation steps. Theterms “light spin” and “heavy spin” are defined in Table 10.5-1 at page716 of the AABB Technical Manual.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a single use system forproducing platelet concentrates (PC). Preferably, the system is in theform of a kit including disposable components supplied sterile indisposable packaging, and having all of the components required to drawblood from the patient, prevent blood coagulation, process the sampleinto platelet concentrate, and deliver the platelet concentrate to asurgical site. It is a particular object of the invention to providesuch a system that will be useful to medical and dental practitioners,including, but not limited to, dentists, periodontists, and oral andmaxillofacial surgeons.

The invention in one of its aspects provides a bag set comprising twobags joined by a tube which includes a built-in sample site at thesecond bag and has sloped top surface geometry at both bags for improvedand more efficient cell separation and collection. This new bag set maybe pre-charged with an anticoagulant. A preferred size range is 50-100ml, but the invention is not limited to any particular size range.

In another aspect of the invention, each bag consists of twocompartments, the first for the sedimentation of cellular material andthe second to serve as an inflatable device for the purpose ofexpressing supernatant liquid from the first compartment.

In still another aspect, the invention provides a bifurcated centrifugebucket having two wells, into each of which one of the cell bags isplaced together with an inflatable device, and a means successively toinflate each inflatable device to perform each expression step followingthe soft spin and the heavy spin, thereby eliminating the step ofremoving the bag set from the bucket after each spin. In a furtheraspect, the invention provides means to express the supernatant liquidfrom within the bucket, thereby eliminating the need to remove the bagset from the bucket after the heavy spin.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is disclosed in greater detail with reference to theaccompanying drawings.

FIG. 1 illustrates a set of two bags according to the invention.

FIG. 2 shows the bag set in a bifurcated centrifuge bucket with adjacentinflatable third and fourth respective bags.

FIG. 3 illustrates the third bag being inflated.

FIG. 4 illustrates the fourth bag being inflated.

FIGS. 5a, b and c illustrate a two chamber bag.

FIG. 5a is a schematic side view of the two chamber bag.

FIG. 5b is a sectional edge view of the bag of FIG. 5a.

FIG. 5c is a top sectional view showing the tubulations which provideaccess to the bag of FIG. 5a.

FIG. 6 is a plan view of a unitary two bag set.

FIG. 7 illustrates the bag set of FIG. 6 assembled to a supporting coverfor the centrifuge bucket.

FIG. 8 is an isometric view of a centrifuge bucket.

FIG. 9 illustrates a two bag set attached to a rigid u-shaped bridge.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIGS. 1-4 illustrate the principles by which bags of the inventionoperate. FIGS. 5-9 illustrate preferred embodiments.

In FIG. 1, a standard needle set (not shown) may be coupled via accesstube 10 to a first bag 12 which is connected via a transfer tube 14 to asecond bag 16. A sample site is provided at an access tube 18 fitted tothe second bag. The top wall 13, 15 of each bag may be sloped as shownfor more efficient cell separation and collection. The principles onwhich invention operates are schematically illustrated in FIGS. 2-4.

In FIG. 2, the bag set 12, 16 is shown in a bifurcated centrifuge bucket20 having two wells 24, 26 separated by a partition 21. Each cell bag12, 16 is in one of the respective wells 24, 26 together with a third orfourth inflatable bag 22, 28, respectively, which is not connected tothe interior of the associated cell bag. The transfer tube 14 connectsthe interior of the two cell bags 12, 16. Each inflatable bag has anaccess tube 22′, 28′, respectively. Each of the access tubes, 10, 18,22′ and 28′ may be furnished with a valve 30 to control access to theinterior of the respective bags. Transfer tube 14 may also be providedwith a valve 30, as shown, to isolate the cell bags duringcentrifugation. The fourth inflatable bag 28 is shorter than itscompanion cell bag 16, so that a desired volume (e.g., about 5 ml) ofplasma concentrate will be left in bag 16 when bag 28 is inflated to adesired pressure.

In use, the first bag 12 is charged with the patient's blood sample inpreparation for the soft spin. The inflatable bags 22 and 28 are notinflated. The contents of the bucket 20 are then subjected to a softspin as described above. After the soft spin, as shown in FIG. 3, a pump(not shown) or other air source is connected via the access tube 22′ tothe third bag 22 and the third bag is inflated, squeezing the first bag12 and forcing the plasma fraction over the transfer tube 14 into thesecond bag 16, leaving the red cell fraction behind in the first bag.The contents of the bucket 20 are then subjected to a heavy spin, asdescribed above. The third bag may be left inflated during centrifugingof the bucket and its contents. Following the heavy spin, the contentsof the second bag 16 are a pellet of platelet concentrate 29 (see FIG.4) at the bottom of the bag and platelet-poor plasma above the plateletconcentrate. A pump (not shown) or other air source may be attached tothe access tube 28′ of the smaller fourth bag 28, and that bag isinflated and platelet-poor plasma may be forced into the first bag 12via the transfer tube 14, as shown in FIG. 4. Expression is continueduntil the platelet poor plasma above the platelet concentrate isexpressed into first bag 12, leaving the platelet rich plasma in thesecond bag 16. With this new arrangement of the invention, the plateletconcentrate fraction is processed into the second bag 16 without a needto remove the bags from the centrifuge bucket during the process.Further according to the invention, the platelet concentrate can beremoved from the second bag 16 via the sample site tube 18 using a knownextraction syringe.

FIGS. 5a, 5 b and 5 c illustrate a two chamber bag 40 which combines acollection chamber 42 and an expression chamber 44 in a singlestructure. This bag 40 corresponds to bags 16 and 28 in FIGS. 2-4. Inthe edge view shown in FIG. 5b, three sheets 52, 54 and 56 are joined attheir peripheries with a weld seam 46 (see FIG. 5a). Typically, thesheets will be of a flexible plastic. The outer sheets 52 and 56 areshown expanded for clarity. In addition, for use of the collectionchamber 42 for platelet collection (e.g., bag 16 in FIG. 1), a secondweld seam 48 joins the intermediate sheet 54 to the expression chambersheet 56 to shorten the expression chamber so as to isolate the desiredvolume of platelet concentrate with the PC produced by the invention.FIG. 5b illustrates the effect of inflating the expression chamber 44. Asimilar two chamber structure 70 (see FIG. 6), without the second weldseam 48, is the equivalent of the first bag 12 and its associatedexpression device 22 shown in FIGS. 2-4.

As shown in FIG. 5a, tubulations 58, 64 and 68 are provided in thisintegrated structure 40 for providing access to the chambers 42 and 44(FIG. 5b). The first tubulation 58 is sealed between the sheets 54 and56 defining the expression cavity 44, and provides access correspondingto the access tube 28′ leading into the inflatable bag 28 in FIG. 2. Thesecond tubulation 64 is sealed between the sheets 52 and 54 defining theplatelet collection chamber 42, and provides access for a transfer tube(e.g., tube 14 in FIG. 1). The third tubulation 68 is similarly providedinto the collection chamber, and provides access corresponding to thesample site tube 18 in FIG. 1. A top view, FIG. 5c, further illustratesthe tubulations 58, 64 and 68, providing access to expression cavity 44and collection chamber 42 of FIG. 5b.

FIG. 6 shows a pair of two chamber structures 40, 70 that may be joinedby an optional bridge 80 between their respective ends that are fittedwith tubulations (58, 64 and 68 for structure 40 and 58 ₁, 64 ₁ and 68 ₁for structure 70) to constitute the bag set 85. The bridge may also beomitted. As shown, structure 40 includes platelet collection chamber 42(FIG. 5b) corresponding to bag 16 in FIGS. 2-4 (facing upward) andexpression cavity 44 (FIG. 5b) corresponding to bag 28 in FIGS. 2-4(facing downward). Structure 70 includes a collection chambercorresponding to bag 12 in FIGS. 2-4 (facing upward) and an expressioncavity (facing downward) corresponding to bag 22 in FIGS. 2-4. Thetubulations 58, 64 and 68 shown in FIG. 5 are shown in FIG. 6, with thecorresponding tabulations 58 ₁, 64 ₁ and 68 ₁ associated with structure70. In use, this bag set is placed in the bifurcated bucket 20 (FIGS.2-4), with the structure 70 corresponding to cell bag 12 in well 24, andthe structure 40 corresponding to cell bag 16 in well 26. The optionalbridge 80 may be flexible or rigid but, in either case, it would contactpartition 21 (FIGS. 2-4) with the pairs of bags on the desired side ofthe centrifuge bucket. As shown, the bridge is flexible and may be apart of the two chamber structures. Alternatively, the bridge could be arelatively rigid plastic molded in a U-shape to fit over the partition21 as illustrated in FIG. 9.

The installation of the bag set 85 in a supporting cover 89, ready forinstallation in a bifurcated bucket (20 in FIGS. 2-4 and 90 in FIG. 8)is shown in FIGS. 7-8. In FIG. 7, the assembled bags are shown as theywould be seen if 40 and 70 of FIG. 6 were folded at the middle andviewed from the side of FIG. 6. The larger two chamber structure 70 isat the right of the drawing, and the smaller two chamber structure 40,used to collect the PC product, is at the left in FIG. 7. Thetubulations provided for access to the bags that contain blood or bloodproducts may be fitted with valves 84, 88. These valves have sufficientmass to require restraint against moving into the wells 24, 26 (seeFIGS. 2-4) under centrifugal force, and supporting cover 89 is providedto support and restrain them against such movement and to facilitatemaking and breaking connections to the valves.

Supporting cover 89 is shown in FIG. 8 without the two chamberstructures 40 and 70 of FIG. 7. In FIG. 8, it can be seen that thesupporting cover 89 is intended to seat on the centrifuge bucket 90. Thetwo chamber structures 40 and 70 will be inserted into the two sides ofthe centrifuge bucket, where they will be used according to theprocedure described connection with FIGS. 2-4. The centrifuge bucketwill typically be made of a plastic, which may be clear or translucentto facilitate observation of the processing of blood into its componentsas described above.

What is claimed is:
 1. A pair of compartmented containers for use inseparating blood into component red cells, platelet-poor plasma, andplatelet concentrate comprising two integrated structures, each of saidstructures consisting of three flexible sheets sealed at the edges toform a first cavity and a second cavity, each of the first cavitiesadapted to hold blood components and each of the second cavities adaptedto receive air under pressure, said integrated structures havingtubulations to provide access to the interior of said cavities, theinteriors of the first cavities being connected together by a hollowtubing extending between said tubulations, said second cavities adaptedto expand under pressure to compress respective said first cavities inorder to expel contents therefrom, said pair of integrated structuresbeing adapted to fit within a centrifuge bucket having an internal wallfor separating said integrated structures, wherein one of saidintegrated structures has a weld seam joining one of said flexiblesheets to an intermediate flexible sheet to shorten the second cavityformed between said sheets.
 2. A pair of compartmented containers ofclaim 1, wherein at least one of said compartmented containers has asloped top edge adjacent said tubulations to provide efficientcollection and separation of blood components.
 3. A pair ofcompartmented containers of claim 1, wherein said containers areconnected to a rigid u-shaped bridge adapted to contact said internalwall of said centrifuge bucket.
 4. A blood platelet collection systemcomprising: a. a centrifuge bucket having an internal partition definingtwo wells therein; b. a pair of compartmented containers for use inseparating blood into component red cells, platelet-poor plasma, andplatelet concentrate comprising two integrated structures, each of saidstructures consisting of three flexible sheets sealed at the edges toform a first cavity and a second cavity, each of the first cavitiesadapted to hold blood components and each of the second cavities adaptedto receive air under pressure, said integrated structures havingtubulations to provide access to the interior of said cavities, theinteriors of the first cavities being connected together by a hollowtubing extending between said tubulations, said second cavities adaptedto expand under pressure to compress respective said first cavities inorder to expel contents therefrom, each of said integrated structuresbeing adapted to fit within a respective well of said centrifuge bucket;c. a cover for said centrifuge bucket providing access to saidtubulations and for restraining valves connected to said tubulationsagainst centrifuged force.
 5. A blood platelet collection system ofclaim 4 wherein one of said integrated structures has a weld seamjoining one of said flexible sheets to an intermediate flexible sheet toshorten the second cavity formed between said sheets.
 6. A bloodplatelet collection system of claim 4 wherein at least one of saidcompartmented containers has a sloped top edge adjacent said tubulationsto provide efficient collection and separation of blood components.
 7. Ablood platelet collection system of claim 4 wherein said compartmentedcontainers are connected to a rigid u-shaped bridge adapted to contactsaid internal partition of said centrifuge bucket.